Modified solution combustion route for the preparation of plasma sprayable ceria powder

Plasma sprayable grade ceria powder was prepared by the solution combustion method. This is the first report on the application of solution combustion for the synthesis of plasma sprayable grade oxide powders. The fuels and fuel ratios used in the solution combustion were modified to achieve adequate flowability. It was found that when a mixture of fuels like glycine and ammonium acetate was used, the combustion process yielded larger agglomerates. Phase purity of the powders was confirmed by powder XRD. The morphology of the particles was determined by scanning electron microscopy.     

Influence of cell shape and aggregate formation on the optical properties of flowing whole blood

We studied the influence of shape and secondary, or intercellular, organization on the absorption and scattering properties of red blood cells to determine whether these properties are of any practical significance for optical evaluation of whole blood and its constituents. A series of measurements of transmittance and reflectance of light from bovine blood in a flow cuvette was conducted with a 650-900-nm integrating sphere at shear rates of 0-1600 s(-1), from which the influence of cell orientation, elongation, and aggregate formation on the absorption (mu(a)) and the reduced scattering (mu(s)') coefficients could be quantified. Aggregation was accompanied by a decrease of 4% in mu(s)' compared with the value in randomly oriented single cells. Increasing the degree of cell alignment and elongation as a result of increasing shear rate reduced mu(s)' by 6% and mu(a) by 3%, evaluated at a shear rate of 1600 s(-1). Comparison with T-matrix computations for oblate- and prolate-shaped cells with corresponding elongation and orientation indicates that the optical properties of whole blood are determined by those of its individual cells, though influenced by a collective scattering factor that depends on the cell-to-cell organization. We demonstrate that cell morphological changes must be taken into consideration when one is conducting whole blood spectroscopy.     

Properties of a reactive‐graphitic‐carbon‐nanofibers‐reinforced epoxy

Our previous studies showed that herringbone graphitic GNFs surface‐derivatized with reactive linker molecules bearing pendant primary amino functional groups capable of binding covalently to epoxy resins. Of special importance, herringbone GNFs derivatized with 3,4′‐oxydianiline (GNF‐ODA) were found to react with neat butyl glycidyl ether to form mono‐, di‐, tri‐, and tetra‐glycidyl oligomers covalently coupled to the ODA pendant amino group. The resulting reactive GNF‐ODA (butyl glycidyl)_n nanofibers, r‐GNF‐ODA, are especially well suited for reactive, covalent incorporation into epoxy resins during thermal curing. Based on these studies, nanocomposites reinforced by the r‐GNF‐ODA nanofibers at nanofiber loadings of 0.15–1.3 wt% were prepared. Flexural property of cured r‐GNF‐ODA/epoxy nanocomposites were measured through three‐point‐bending tests. Thermal properties, including glass transition temperature (T_g) and coefficient of thermal expansion (CTE) for the nanocomposites, were investigated using thermal mechanical analysis. The nanocomposites containing 0.3 wt% of the nanofibers gives the highest mechanical properties. At this 0.3‐wt% fiber loading, the flexural strength, modulus and breaking strain of the particular nanocomposite are increased by about 26, 20, and 30%, respectively, compared to that of pure epoxy matrix. Moreover, the T_g value is the highest for this nanocomposite, 14°C higher than that of pure epoxy. The almost constant change in CTEs before and after T_g, and very close to the change of pure epoxy, is in agreement with our previous study results on a chemical bond existing between the r‐GNF‐ODA nanofibers and epoxy resin in the resulting nanocomposites. POLYM. COMPOS., 28:605–611, 2007. © 2007 Society of Plastics Engineers     

Hot Deformation Behaviour of AA2014–10 wt% SiC Composite

The hot compression behaviour of AA2014 alloy having 10 wt% SiC particles was studied over a wide range of temperatures (ambient to 400 °C) and strain rates (0.01–10/s). The results were compared with those obtained from identical tests performed on the base alloy to understand the effect of the SiC particle reinforcement. Processing maps were generated using dynamic materials model from the flow stress of the samples. Microstructures of the deformed samples suggest the occurrence of dynamic recrystallization at high temperatures and low strain rate. Flow localization and adiabatic shear bands were observed at higher strain rates and temperatures. The lack of cohesion between SiC particles and the matrix was found to be responsible for the deteriorating deformation behavior of the composite over most of the processing domains. The activation energy for high temperature deformation in the presence of the SiC particles in the alloy was found to be significantly higher than that of the matrix. This makes deformation processing of the composite more difficult than that of the matrix.     

Electron-induced dissociation of singly charged organic cations as a tool for structural characterization of pharmaceutical type molecules

Collision-induced dissociation (CID) and electron-induced dissociation (EID) have been investigated for a selection of small, singly charged organic molecules of pharmaceutical interest. Comparison of these techniques has shown that EID carried out on an FTICR MS and CID performed on a linear ion trap MS produce complementary data. In a study of 33 molecule-cations, EID generated over 300 product ions compared to 190 product ions by CID with an average of only 3 product ions per precursor ion common to both tandem MS techniques. Even multiple stages of CID failed to generate many of the product ions observed following EID. The charge carrying species is also shown to have a very significant effect on the degree of fragmentation and types of product ion resulting from EID. Protonated species behave much like the ammonium adduct with suggestion of a hydrogen atom from the charge carrying species strongly affecting the fragmentation mechanism. Sodium and potassium are retained by nearly every product ion formed from [M + Na](+) or [M + K](+) and provide information to complement the EID of [M + H](+) or [M + NH(4)](+). In summary, EID is proven to be a fitting partner to CID in the structural elucidation of small singly charged ions and by studying EID of a molecule-ion holding different charge carrying species, an even greater depth of detail can be obtained for functional groups commonly used in synthetic chemistry.     

Preparation, characterization and properties of acid functionalized multi-walled carbon nanotube reinforced thermoplastic polyurethane nanocomposites

The multi-walled carbon nanotube (MWNT) reinforced thermoplastic polyurethane (TPU) nanocomposites were prepared through melt compounding method followed by compression molding. The spectroscopic study indicated that a strong interfacial interaction was developed between carbon nanotube (CNT) and the TPU matrix in the nanocomposites. The microscopic observation showed that the CNTs were homogeneously dispersed throughout the TPU matrix well apart from a few clusters. The results from thermal analysis indicated that the glass transition temperature (T_g) and storage modulus (E′) of the nanocomposites were increased with increase in CNTs content and their thermal stability were also improved in comparison with pure TPU matrix. The rheological analysis showed the low frequency plateau of shear modulus and the shear thinning behavior of the nanocomposites. The electrical behaviors of the nanocomposites are increased with increase in weight percent (wt%) of CNT loading. The mechanical properties of nanocomposites were substantially improved by the incorporation of CNTs into the TPU matrix.     

Optical absorption spectrum of Ni2 ions in sodium ammonium sulphate dihydrate single crystal

The Optical absorption spectrum of Ni²⁺ in sodium ammonium sulphate dihydrate single crystal has been studied at room and liquid nitrogen temperatures. The spectrum shows characteristic features of Ni²⁺ ions in octahedral crystalline fields. The splitting in one of the bands at liquid nitrogen temperature has been explained as due to spin-orbit interaction. The observed band positions have been fitted with the parameters B, C, Dq and E     

Lower bound buckling strength of axially loaded sandwich cylindrical shell under lateral pressure

Effects of the lateral pressure on the FEM and reduced stiffness lower bound buckling strength of axially loaded sandwich cylindrical shell are examined. Further, a reduced stiffness lower bound buckling strength for the axially loaded sandwich cylindrical shell under lateral pressure is proposed. The effect of the lateral pressure on the FEM and reduced stiffness lower bounds are corresponding; it causes them to reduce slightly. However, reduced stiffness buckling mode shape remains the same. In addition, the proposed reduced stiffness lower bound buckling strength is shown to provide effective and valid for cores having different shear stiffness. It provides comparatively close lower bounds to short axially loaded sandwich cylindrical shells under lateral pressure. Further, it provides a safe lower bound that does not depend on precise geometrical imperfection spectra and lateral pressure and it is simple and easy to employ.     

Synthesis of a novel efficient antioxidant for use in lubes and biodiesel

A novel phenolic ester Bz-3-tBz was synthesized by reaction between 1,3,5-benzenetricarboxylic acid chloride and 3,5-di-tert-butyl-4-hydroxybenyl alcohol using N,N’-dimethylacetamide solvent and N,N’-dimethylaminopyridine as catalyst. The additive Bz-3-tBz was characterized by CHN, FT-IR, NMR and TG. The Bz-3-tBz was then evaluated as antioxidant additive in polyol by the rotatory bomb oxidation test (RBOT) as per ASTM D2272. The RBOT time for the blank sample containing only polyol base was observed to be 6 min 43 sec. It was observed that Bz-3-tBz in 3000 ppm concentration enhanced the RBOT time to the 15 min 46 sec. It was a significant increase of 2.35 times. The oxidation stability of biodiesel was also found to be increased when Bz-3-tBz was added in to it. The value of induction time determined by the Rancimat test for the biodiesel at 130°C was 0.60 h which was increased to 3.14 h at 2000 ppm Bz-3-tBz concentration.     

Determination of zonal boundaries in articular cartilage using infrared dichroism

To determine the sub-tissue structural zonal boundaries in articular cartilage, a novel infrared (IR) microscopic imaging method based on the dichroic nature of the amide components has been developed and is discussed in this article. Thin canine cartilage-bone sections embedded in paraffin as well as in poly(methyl methyacrylate) (PMMA) were imaged under two orthogonal polarization states at 6.25 mum pixel size. The depth-dependent anisotropy of the amide components at perpendicular polarization states attributed by the collagen constituent in cartilage was analyzed. Since the transitional zone fibers are randomly arranged and the dichroic ratio value reaches unity in this zone, it is possible to identify the transitional zone boundaries, thus dividing the whole-depth tissue into three structural zones (superficial, transitional and radial). The zone division results from the infrared method agree well with the results from the established polarized light microscopy (PLM) method, which promises the potential of infrared imaging as an independent technique for the zonal boundary determination. The advantages of this dichroic ratio method are (1) it is independent of mode of operation (transmission/reflection), (2) it is independent of sample thickness, (3) either a polarizer or an analyzer can be used in experiments to determine zonal boundaries, and (4) it is sample orientation independent.